1. Field of the Invention
The present invention relates to touch panels and display device using the same and, particularly, to a carbon nanotube based touch panel and a display device using the same.
2. Discussion of Related Art
Following the advancement in recent years of various electronic apparatuses, such as mobile phones, car navigation systems and the like, toward high performance and diversification, there has been continuous growth in the number of electronic apparatuses equipped with optically transparent touch panels in front of their respective display devices (e.g., liquid crystal panels). A user of any such electronic apparatus operates it by pressing a touch panel with a finger, a pen, stylus, or another like tool while visually observing the display device through the touch panel. A demand thus exists for such touch panels that are superior in visibility and reliable in operation.
At present, different types of touch panels, including a resistance-type, a capacitance-type, an infrared-type and a surface sound wave-type have been developed. Due to the high accuracy and a low-cost of the production thereof, the resistance-type touch panels have been widely used.
A conventional resistance-type touch panel includes an upper substrate, a lower substrate and a plurality of dot spacers. The upper substrate includes an optically transparent upper conductive layer formed on a lower surface thereof, and two upper electrodes connected to the optically transparent upper conductive layer at two edges along the X direction. The lower substrate includes an optically transparent lower conductive layer formed on an upper surface thereof, and two lower electrodes connected to the optically transparent upper conductive layer at two edges along the Y direction. The plurality of dot spacers is formed between the optically transparent upper conductive layer and the optically transparent lower conductive layer. The optically transparent upper conductive layer and the optically transparent lower conductive layer are formed of conductive indium tin oxide (ITO). The upper electrodes and the lower electrodes are formed of a silver paste layer.
In operation, an upper surface of the upper substrate is pressed with a finger, a pen or the like tool, and visual observation of a screen on the display device provided on a back side of the touch panel is allowed. This causes the upper substrate to be deformed, and the upper conductive layer thus comes in contact with the lower conductive layer at the position where pressing occurs. Voltages are applied successively from an electronic circuit to the optically transparent upper conductive layer and the optically transparent lower conductive layer. Thus, the deformed position can be detected by the electronic circuit.
However, the material of the electrodes such as metal has poor wearability/durability and low chemical endurance. Further, when the substrate is deformable and made of soft material, the electrodes formed on the substrate is easily to be destroyed and break off during operation. The above-mentioned problems of the metallic electrodes make for a touch panel with low sensitivity, accuracy and durability. Additionally, the cost for forming the metallic electrodes is relatively high.
What is needed, therefore, is to provide a durable touch panel and a display device using the same having high sensitivity, accuracy, and brightness.